Adrenergic pathway in the inhibition of pancreatic secretion by peptide YY in dogs.

Peptide YY (PYY) is released by perfusion of an ileocolonic segment with oleate and inhibits exocrine pancreatic secretion. This study was designed to determine the role of the adrenergic pathway in the PYY-induced inhibition of pancreatic secretion. After intravenous administration of PYY, there was a dose-dependent inhibition of pancreatic HCO3 and protein responses to secretin, cholecystokinin, and feeding in conscious dogs and a reduction in pancreatic blood flow in anesthetized animals. These inhibitory effects of PYY on pancreatic secretion and blood flow were abolished in the presence of combined phentolamine and propranolol. Ileal perfusion with oleate caused a rise in plasma PYY levels similar to that observed after intravenous infusion of exogenous PYY. Combined alpha- and beta-adrenergic blockade also antagonized the effects of ileal perfusion with oleate on hormonal and postprandial pancreatic secretion. We conclude that exogenous PYY or endogenous PYY released by ileal oleate inhibits pancreatic secretory responses to exogenous secretin, cholecystokinin, or a meal and causes pancreatic vasoconstriction. Both these effects are mediated, at least in part, by the adrenergic pathway.